Lubricating oil compositions containing polymeric additives



United States Patent LUBRICATING OIL COMPOSITIONS CONTAINING POLYMERIC ADDITIVES Willard E. Catlin, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware N0 Drawing. Application February 16, 1952, Serial No. 271,977

8 Claims. (Cl. 252-515) This invention relates to lubricants and, more particularly, to new lubricating oil compositions of improved properties. The present application is a continuation-inpart of applicants copending application Serial No. 214,- 853, filed March 9, 1951, now abandoned.

The principal market for lubricating oils is in internal combustion engines the efficiency of which depends to a large degree on the quality of the crankcase oils employed. A major problem in the operation of both spark ignition and diesel engines results from the tendency of conventional crankcase oils to undergo oxidation and other chemical changes that lead to the formation of carbon, resins, and insoluble varnish-like gums that deposit on moving engine parts and separate as sludge that markedly impairs the lubricating properties of the oil. A major contribution to the sludge may also arise from decomposition of the fuel. Deposition of sludge on piston surfaces and around piston rings is particularly damaging. It is known that sludge formation and gum deposition are especially severe in light duty engine operation as exemplified by intermittent use of passenger automobiles and light trucks.

Many materials have been added to lubricating oils to improve them and considerable knowledge of such adjuvants has been gained. However, no detergent or sludge dispersant additive for oils has heretofore been proposed that provides more than a partial answer to the problem of preventing sludge formation and varnish deposition in engines. Moreover, known oil detergents in many cases increase the rate of accumulation of inorganic deposits within the combustion chambers of internal combustion engines.

An object of the present invention is to provide improved lubricating oil compositions. A further object is to provide dispersive lubricating oil compositions having superior resistance to sludge formation and varnish deposition in internal combustion engines. A still further object is to provide such lubricating oil compositions having a low rate of change of viscosity with temperature. Other objects will be apparent from the description of the invention given hereinafter.

The above objects are accomplished according to the present invention by incorporating in a lubricating oil at least 0.1% by weight of the lubricating oil, of an oilsoluble, basic amino nitrogen-containing addition-type polymer of a plurality of polymerizable ethylenically unsaturated compounds, at least one of which is amino-free and contains from 8 to about 18 carbon atoms in an aliphatic hydrocarbon chain, which in the polymer is not part of the main polymer chain, preferably predominantly straight chain in nature, and one of which as it exists in the polymer contains a basic amino nitrogen in the side chain, said polymer containing 0.1% to 3.5%, by weight thereof, of basic amino nitrogen.

The optimum proportion of polymer in the lubricating oil will be determined by its inherent viscosity, which can be within the range of 0.1 to 3.0 as determined at 0.1% weight/volume concentration in benzene at 25 C., and

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will range between 0.1% and 20% by weight of the lubricating oil. From a practical point of view, 0.25% to 10% of the polymer additive having an inherent viscosity between about 0.2 and 1.0 normally will be found to give optimum results.

Although the mechanism by which the lubricant compositions of this invention operate is not known, experimental work both in laboratory and engine tests has established certain basic requirements for the addition-type polymers as regards compositions, structure, and physical properties. For example, it is essential that at least one of the monomeric components employed in making the polymer should introduce an oil-solubilizing or oleophilic structure to insure that the polymer is soluble to the extent of at least 0.1% by weight in naphthenic, paraflinic, or ester type lubricating oils. In addition, the presence of basic amino groups, either primary, secondary, or tertiary, is necessary to impart the unique sludge dispersing properties which characterize these polymers. The proportion of basic amino nitrogen is best expressed in weight percent based on the total copolymer, and should be within the range of 0.1% to 3.5%. Introduction of the basic amino nitrogen structure can be accomplished by the use of at least one monomeric component containing the amino group or by use of a monomer containing a group which is reactive, when present in the polymer, toward ammonia, or primary or secondary nonaromatic amines. These monomers can also contain oleophilic structures that will assist in contributing to the requisite oil solubility. In addition, some of the polymers coming within the scope of this invention can, without sacrificing either oil solubility or dispersing properties, include certain proportions of monomers that do not themselves yield oil soluble polymers.

Copolymers useful in the practice of the invention can be prepared by conventional bulk, solution, or dispersion polymerization methods involving known initiators, including oxygen-yielding compounds, such as benzoyl peroxide, and azo compounds, such as alpha, alpha'-azodiisobutyronitrile. The polymerization processes usually are carried out in an inert atmosphere, e. g., nitrogen or carbon dioxide, at temperatures ranging from 30 C. to 150 C., depending on the catalyst used, and generally at temperatures between 50 C. and 70 CJWhen alpha,alphaazodiisobutyronitrile is used as the catalyst. It is important to carry the copolymerization substantially to completeness so that no unpolymerized monomers remain and the proportions of each component in the final prodnot are essentially those of the original monomer mixture.

The following examples wherein all parts are by weight unless otherwise stated, illustrate typical polymers adapted for use in the present invention.

EXAMPLE I EXAMPLE II 1020 parts of technical lauryl methacrylate, parts of methacrylanilide, 60 parts of beta-diethylaminoethyl methyacrylate, 300 parts of mineral oil and 3.6 parts of alpha,alpha'-azodiisobutyronitrile were agitated together at 60:2" C. under nitrogen. After two hours some thickening of the charge was observed and during the next 16 hours, 900 parts more of mineral oil was r? radually as the polymerization proceeded. There obtained a barely stirrable oil solution of :1 er of the three polymerizable components in esally the proportions charged, i. e., 86.4/85/51.

The technical lauryl methacrylate used in the preparation above is the methacrylic acid ester of technical lauryl alcohol which is obtained by reduction of the fatty acids of coconut oil and is a mixture of saturated straight chain alcohols ranging from about to 18 carbon atoms. A typical example will contain approximately 3% C10, 61% C12, 23% C14, 11% C16 and 2% C18 alcohols.

EXAMPLE III 170 parts of technical lauryl methacrylate, 20 parts of methacrjylanilide (N-phenylmethacrylamide), 10 parts of glycidyl methacrylate and 1.2 parts of alpha,alpha-azodiisobutyronitrile were heated together in a polymerization reactor for 8 hours at C., as in Example 1.

The 10/5 lauryl methacrylate/methacrylanilide/glymethacrylate units by the diamylamine to give units con- 3 taining gamma-diamylamino-beta-hydroxypropyl radicals as more fully disclosed in application Serial No. 176,918, filed July 31, 1950, now abandoned, in the name of M. E. Cupe'ry, assigned to the as'signee of this application. The final product is thus a lauryl methacrylate/methacrylanilide/g'amm'a-diamylamino beta hydroxypropyl methacrylate copolymer.

EXAMPLE IV parts of technical lauryl methacrylate and 10 parts of glycidyl methacrylate were copolymerized as in Example II by heating at 60 C. for 24 hours in solution in 100 parts of highly refined petroleum white oil in the presence of 0.6 part of alpha,alpha-azodiisobutyronitrile. To the oil solution of the copolymer thus obtained there was then added 9.4 parts of technical diamylarnine (0.85 molar proportion based on the copolymer) and the mixture was heated to 80 C. for about 1 hour to effect reaction of the diamylamine with the oxirane rings in the glycidyl methacrylate units in the copolymer in the manner explained in Example III, to obtain a white oil solution of a lauryl methacrylate/glycidyl methacrylate/gamma-diamylamino-beta-hydroxypropyl methacrylate copolymer.

EXAMPLE V A mixture of 19 parts of vinyl laurate, 1 part of allyl glycidyl ether and 0.12 part of alpha,alpha-azodiisobutyronitrile was heated for 6 hours at 65 C. as in Example III. To the resulting /5 vinyl laurate/allyl glycidyl ether copolymer was added 1.1 parts of technical diamylamine and the reaction mixture allowed to stand for several days at room temperature. There was thus obtained an oil-soluble vinyl laurate/allyl glycidyl ether/allyl gamma diamylamino beta hydroxypropyl ether copolymer.

EXAMPLE VI A pressure-resistant reaction vessel was charged with 20 parts of beta-diethylami'noethyl methacrylate, 50 parts of 2 -ethylhexyl 'acrylate 'and 0.5 part of alpha-alphaazodiisobutyronitrile. The vessel was closed-flushed with nitrogen and evacuated, pressured with isobutylene under 3000 atmospheres pressure, and heated with agitation for 4 hours at about 65 C. The reactor was then cooled, vented to the atmosphere and the resinous product re- The resultant mixture was moved. There was thus obtained a 69/ 16.4/ 14.6 2-ethylhexyl acrylate/beta-diethylaminoethyl methacrylate/isobutylene copolymer as an oil-soluble, viscous, tacky resin.

Another copolymerization reaction was carried out as above, with 40 parts of lauryl methacrylate, 10 parts of beta-dimethylaminoethyl methacrylate, 50 parts of benzene, 0.5 part of alpha,alpha-azodiisobutyronitrile and ethylene under 1000 atmospheres pressure. There was thus obtained a 64/18/18 lauryl methacrylate/beta-dimethyl-aminoethyl methacrylate/ethylene copolymer as an oil-soluble, viscous, tacky resin.

EXAMPLE VII 80 parts of sec.-capryl methacrylate (B. P. 70-72 C./0.50.7 mm. of mercury), prepared by ester interchange of sec.-capryl alcohol with methyl methacrylate in the presence of tetraisopropyl titanate as catalyst (as was fully disclosed in application Serial No. 256,373, filed November 14, 1951, in the name of I. H. Haslam and assigned to the assignee of the present application), 20 parts of beta-diethylaminoethyl methacrylate and 0.5 part of alpha,alpha'-azodiisobutyronitrile were heated together for 5 hours at 65 C. in the manner of Example III above. There was thus obtained an 80/20 sec.-capryl methacrylate/betadiethylaminoethyl methacrylate copolymer as an oil-soluble, soft, sticky, rubbery resin.

EXAMPLE VIII parts of tridecyl methacrylate from a commercially available, branched-chain primary tridecyl alcohol, 40 parts of beta-diethylaminoethyl methacrylate, 60 parts of styrene and 1 part of alpha,alpha-azodiisobutyronitrile were heated for 20 hours at 65 C. in the manner of Example Ill. There was thus obtained a 50/20/ 30 tridecyl methacrylate/ beta-diethylaminoethyl methacrylate/ styrene copolymer as an oil-soluble, rather stiff, rubbery resin.

EXAMPLE IX A mixture of 180 parts of lauryl methacrylate, 14.5 arts of N-(beta-vinyloxyethylformamide) 67" C./ 0.9 mm. mercury, prepared by the aminolysis of methyl formate with beta-vinyloxyethyl amine as disclosed in application Serial No. 269,339, filed January 31, 1952, now abandoned, in the name of John C. Saucr and assigned to the assignee of the present application), and 1 part of alpha,alpha-azodiisobutyronitrile were heated for 4 hours at 65 C. in the manner of Example III. There was thus obtained a lauryl methacrylate/N-(beta-vinyloxyethyl).formamide copolymer as an oil-soluble, clear, tacky, rubber-like resin.

EXAMPLE 1X-A To a solution of 90 parts of the above lauryl methacrylate/N-(beta-vinyloxyethyl)formamide copolyrner in about 400 parts of benzene was added parts of 18 aqueous hydrochloric acid and the resulting mixture heated at a gentle reflux for one hour with stirring. The resulting creamy emulsion was treated with an excess of 20% aqueous sodium hydroxide solution and the organic layer thereby obtained removed, washed well with water and any retained benzene-water removed by evaporation at steam bath temperatures under atmospheric pressure and finally under reduced pressure. There was thus obtained an oil-soluble, highly viscous, tacky copolymer which upon analysis was found to contain 0.25% primary amino nitrogen, indicating the presence of 1.4% combined beta-vinyloxyethyl amine groups.

EXAMPLE X A branched chain ar-dodecylstyrene was prepared by acetylation of a commercial mixture of detergent intermediate type, branched chain dodecylbenze'nes with acetyl chloride in the presence of aluminum chloride, selective catalytic hydrogenationof the resulting ketone with nickel catalyst, and dehydration of the carbinol by refluxing with xylene containing iodine. 9;parts of the ar-dodecylstyrene fraction (B. P. 135-140" C./4 of mercury), 1 part of beta-diethylaminoethyl methacrylate and 0.07 part of alpha,alpha-azodiisobutyronitrile were heated for 5 hours at 65 C. There was obtained a 90/10 ardodecylstyrene/beta-diethylaminoethyl methacrylate copolymer as. an oil-soluble, highly viscous product, tacky at room temperature.

The polymer additives used in preparing the dispersive lubricating compositions of this invention can be incorporated in the lubricating oils by simply blending with stirring at ordinary temperature or, if desired, a mixture of the oil and the additive polymer or polymers can be heated to elevated temperatures, e. g., 100-130" C. with agitation. In many instances it is convenient to carry out the preparation of the additive polymer directly in solution in a lubricating oil since the addition of such solutions to lubricating oils to obtain the desired concentration offers a ready method of incorporating the additive polymer in the lubricating oil.

The concentration of the additive polymer used in the lubricating oil will not normally be less than 0.1%, nor exceed 20% by Weight of the oil. However, master batches containing 50% or higher of the additive polymers by weight of the oil may be made for convenience in handling prior to preparation of large batches of the lubricant compositions. Thus, a 50% solution of one or more of the additive polymers in a lubricating oil will serve by direct addition to further quantities of the base oil to produce approximately a 50-fold larger batch of the final lubricating composition. The lubricating oils may contain in addition to the herein considered polymers conventional modifiers (in solution or suspension) which impart other desirable characteristics to the oil, e. g., antioxidants, corrosion inhibitors, and the like.

Although the preferred compositions of this invention comprise the lubricating compositions made up from oils boiling at about 345 C. or above at 1 atm. pressure, the same additive polymers can be added to power converting fluids such as used in automatic transmissions, particularly those of SAE-20 to 30 grade oil, torque converters, and the like, as Well as to hydraulic oils, turbine oils and other such oils, and similarly impart to these other oils the same desirable dispersive, sludge suspending characteristics.

Probably the most important problem currently remaining in the lubricating field is the question of sludge formation and deposition on important working areas in internal combustion engines, particularly under the operating conditions in ordinary stop and go driving. This type of operation, which is typical for urban passenger cars, and in door to door and other similar light driving services, accounts for perhaps as much as three-quarters of all internal combustion engine operations today. This type of operation entails a considerable proportion of starting, idling, constant shifting with resultant changes in load and torque ratios and short term operating at relatively higher engine speeds, and, in almost all instances, involves operation with the crankcase lubricant at relatively low temperatures. This type of engine operation will be referred to as low-duty operation. Varnish and sludge which form under such low-duty operating conditions have characteristic peculiarities which distinguish them from the varnish and sludge formed under heavy-duty conditions such as exist for internal combustion engines in heavily loaded trucks, tractors, and the like. Consequently, commercial lubricating oil additives, which have been designed for, and operate with moderate success in solving these problems for heavy-duty engine operation, are relatively ineffective in low-duty operation, even when used at higher concentrations which are obviously less desirable from the cost standpoint. Actually, insofar as known, no successful solution to these problems for low-duty operation has yet been taught.

To evaluate in the laboratory under control conditions the suitability of lubricating compositions for this imporamass tant low-duty operation, a special test has been developed to simulate those conditions. This test is similar to a variety of tests employed in the oil industry for the same purposes, and is itself employed by oil companies to a considerable extent because of its superior correlation with results obtained on the road in actual long-term service tests. As will be seen from the data presented in the table below which are discussed in detail there, this test clearly demonstrates the need of a lubricating composition which at reasonable concentrations will promote engine cleanliness under low-duty operation, the ineffectiveness of the presently available materials under these conditions, and, finally, the outstanding behavior of lubricating compositions of this invention containing the oleophilic, basic amino nitrogen-containing additiontype polymers.

This test is carried out using a standard Chevrolet passenger car engine which has been modified so that piston ring land corners are beveled and three of the six oil rings have slots which are only half the normal width to promote oil ring clogging. The various oils are tested as lubricants in clean Chevrolet engines modified as above by operating the engine for two-hour periods under conditions designed to simulate each of the normally encountered driving conditions, i. e., idling, high load-low temperature (as in the period following start-up or in cold weather), and high load-high temperature (as in continued operation). These periods are repeated suc cessively for a total of 96 hours. Specific conditions for the three types of operation are as follows:

L L il h oa 0w 0a 1g Idlmg Tempera- Temperature ture Speed, R. P. M 500 2, 500 2, 500 Load, Brake-Horsepower 0 4 45 Air-Fuel Ratio 9:1 14.5:1 14.511 Coolant Out Temp., F. 100 200 011 Sump Temp., "F 100-125 245 Oil A-Mid-Continent solvent extracted oil, SAE 20 grade, without additives Oil BA commercial oil prepared from oil A, SAE 20 grade, with conventional additives to pass performance specification MIL-0-2l04 Oil C-Oil like B except that it is SAE 30 grade Oil D-Oil A with 1.5% of a 90/ 10 lauryl methacrylate/ beta-diethylaminoethyl methacrylate copolymer. Blend is SAE 30 grade Oil E-Oil D with 0.5% of a commercial antioxidant Oil FOil A with 0.5 of the same antioxidant Oil G--A commercial oil of Mid-Continent origin with conventional additives to pass performance specification MIL-02l04-B, Supplement 1 Oil HA conventionally refined Gulf Coast oil without additives Oil IOil H with 1.5% of a 90/10 lauryl methacrylate/ beta-diethylaminoethyl methacrylate copolymer and 0.5% of the above antioxidant Oil JA solvent extracted Pennsylvania oil without additives Oil KOil I with 1.5% of a 90/ 10 lauryl methacrylate/ beta-diethylaminoethyl methacrylate copolymer and 0.5% of the above antioxidant.

1 flhese additives are, in general, mineral salts of petroleum sulfonates which, In contrast to the additives of this invention, deposit inorganic ash Table I Average are. are ar Score Rating Rating 4. 3 Medium 4. 5 3. 9 4. 9 Nil-Trace 6. 5 5. 2 5.0 L ght 5. b 5.0 8. 3 N l 7. 9 6. 3 9. N11. 7. 8 7. 6 9. 3 Nil 8. 2 6. 4. 0 Nil-Trace- 6. 3 5. 2 5. 8 Trace 6.7 5. 4 5. 3 Nil-Trace. 6. 4 5. 3

*3. 0 Heavy"- a *3. 5 *4. 8 8. 5 Nil g. (15 t6) 4. O 9. 2 Nil-Trace- 7. 8 7. 5

Test was discontinued after 82 hours because of piston seizure.

Oils A through D are related as to source and process of refining. Comparison of the data obtained using oil E with the data obtained for oils B and C demonstrates the superiority of the oleophilic, basic amino nitrogencontaining copolymer additives over the conventional detergent-antioxidant type. Oil G has been particularly recommended for superior low-duty performance. Comparison of the data obtained with this oil and those for oil E demonstrates the outstanding superiority of lubricant compositions containing oleophilic, basic amino nitrogen-containing copolyrners.

Since it is recognized that the source of the crude and the refining methods used in preparing the lubricating oil have a great effect on the performance of lubricant additives, data on oils H and I, J and K have been included in the above table to show the effectiveness of the preferred additive copolyrners in both Gulf Coast and Pennsylvania oils.

Another laboratory test used to evaluate lubricating compositions is the L-4 test carried out in a standard Chevrolet passenger car engine according to the procedure CRC L-4949 in Appendix F of the Laboratory Engine Tests of Sulfur in Motor Gasoline Field Test Fuels, January 1950, by the Coordinating Research Council, Inc. This test is a well-known research procedure used to evaluate the ease of oxidation of an oil, its corrosiveness to bearings, and its effect on general engine cleanliness. Although it does not directly evaluate the most outstanding property of the lubricant compositions of this invention, i. e., detergency, particularly under low-duty operation, it does give results which correlate with the performance of oils under heavy-duty conditions in the field.

Results of this test are reported as (l) a corrosion value which is the weight loss per Whole copper-lead alloy connectingrod bearing and (2) an engine score which is the summation of varnish and/ or sludge ratings on a O to 10 scale for certain engine parts which give a perfect total score of 100. The results shown in Table II below were obtained in this test using the specific lubricating compositions discussed in Table I.

l This value should be 0.25 or less for good performance in the field.

The data in Table 11 indicate (comparison of oils A and D) tnat the oleophilic, basic amino nitrogen-containing addition-type polymers contribute ahigh degree of engine cleanliness but at the same time enhance corrosiveness. This latter effect is usual for dispersant-detergent additives in unstabilized motor oils and is conventionally controlled by the addition of antioxidants as may be seen by comparison of the data obtained with oils D and E. Note that these added antioxidants have no eflect on detergency as may be seen by the data obtained with oil F. The over-all cleanliness and corrosiveness of the lubricant compositions of this invention with conventional added antioxidants demonstrate clearly that these compositions are essentially equivalent to heavy-duty commercial lubricant compositions under heavy-duty operating conditions which constitute a relatively minor proportion of lubricant uses and for which the compositions of the present invention were not particularly designed (comparison of data for oil E with oils C or G). On the other hand, as indicated in the previously discussed lou-duty test, these commercially available, heavy-duty oils fail to combat successfully the problems encountered under the far more important low-duty driving conditions.

Rather than test all new lubricating compositions in the above rather complete engine tests, several much less time-consuming sorting tests (which correlate with the more thorough engine tests and with actual service behavior) are conventionally used in this field to determine the over-all properties and suitability of new lubricating compositions. Data are presented in Tables Hi to VIII demonstrating the outstanding properties exhibited by the dispersive lubricating compositions of this invention in certain of these tests described below:

A. VISCOSITY INDEX AND SLOPE Lubricating oil compositions having a low rate of change of viscosity with temperature are highly desirable. Judgment of the suitability of a lubricating oil composition for use over a Wide range of operating temperatures is afforded by the viscosity index of the oil which is calculated from the measured viscosities (expressed in Centistokes) of the lubricating composition at F and 210 F. by the standard A. S. T. M. method, D-567-4l. In this test lubricating compositions exhibiting the highest viscosity index show the least change in viscosity with change in temperature. An increase of 5 viscosity index units is a significant improvement. In data below, the polymer is added at 1.5% concentration.

Another measurement of value for judging the suitability of lubricating oil compositions is the calculated slope of the line joining the points of intersection of the viscosities of the oil composition at 100 F. plotted as ordinants with the viscosities at 210 F. plotted as abscissas for different concentrations of additives. This slope value'is conveniently calculated from the following equation:

Viscosity of lubricating composition at 100 F.

minus viscosity of lubricating oil alone at 100 F. Viscosity of lubricating composition at 210 F.

minus viscosity of lubricating oil alone at 210 F.

In this calculation, oil-s having the lowest values for slope exhibit the least change in viscosity with changes in temperature.

Slope B. PREFORMED SLUDG-E TESTS The procedure for this test is as follows: To 0.05 g. of the pentane insoluble portion of sludge from oil oxidizcd in an Underwood apparatus dissolved in 20 m1. of benzene and contained in a 50 ml. beaker, is added 10 ml. of a kerosene solution of the additive being evaluated at the desired concentration. The sludge remains in solution at this time. The benzene is then evaporated by heating at 100405 C. for a period or 45 minutes, while the liquid is stirred, using carefully controlled conditions of heating and rate of stirring so as to achieve maximum reproducibility.

The evaporation of benzene leaves the sludge suspended in kerosene since it ,is insoluble in that liquid. Rapid settling of the sludge occurs unless agents are present that tend to suspend or solubilize the material. The settling tendencies of the resultant sysern are observed in 5 ,cc. graduated cylinders.

in the following tables, action of: additives is classified as follows:

Very good-sludge suspension is clear or very slightly hazy after two days in the presence of 0.4% additive.

Good-sludge is suspended but hazy after two days in the presence of 0.4% additive.

Moderate-sludge is not suspended at 0.4% concentration of additive, but is suspended for two days or more by 0.8%.

Poorsludge is not suspended 'by 0.8% additive concentration but settles or coagulates slowly in over half a day.

Negligiblesludge settles or coagulates in less than half a day in the presence of 0.8% additive.

C. LAUSON ENGINE TEST A vitally important property which should be exhibited in the highest degree in good lubricating compositions is the ability of the lubricant to maintain in suspension the sludge normally formed during engine operation, i. e., the ability to prevent sludge deposit-ion on important operating portions of the engine such as the piston rings, the pistons themselves, and the like, under the actual operating conditions encountered in an internal combustion engine. The so-cal-led Lauson engine test (see The 'Oil and Gas Journal, January 8, 1948, p. 59) has been designed to evaluate this property of a lubricant and it is used as a standard in the lubricating field.

The Lauson data reported in the tables below for the various lubricants are obtained in 40-hour runs in a Lauson engine operating at 1840:20 R. P. M. under a load of 1.86 horsepower using a fan brake with the engine operating at a jacket coolant temperature of 350 F. and an oil temperature of 200 F., no crankcase ventilation, an air2fuel ratio of 12.5 10.5: 1, and a spark advance of 25 BTDC. The compositions are scored on the basis of their performance in these engine tests according to the following system: a ring sticking effect is rated at 20 times the percentage of the rings free at the end of the test, thereby making the maximum score for this item 20; piston skirt lacquer formation is rated on the following decreasing scale: no lacquer formation, 10 points; tan lacquer, 8 points; light brown lacquer, 6 points; brown lacquer, 4 points; darker brown lacquer, 2 points; =black lacquer, points, thus leaving the maximum score possible in this property, points; oil-ring blocking is evaluated by multiplying 10 by the percentage of the ring open, thus making the maximum score possible on this effect, 10 points; finally, under piston deposition is rated according to the following decreasing scale: no deposition, 10 points; trace deposition, 8 points; light deposition, 6 points; medium deposition, 4 points; heavy deposition, 2 points; very heavy deposition, 0 points; thereby allotting 10 points to the maximum score on this eifect. Thus, the total maximum score for all four efi'ects is 50 on this scoring method. Normally, the totals arrived at are multiplied by 2 on which basis a perfect score is, of course, 100.

t 10 Table IV.S.4E20 furfural extracted Mid-Continent oii Preformed Lauson No. Polymer Added Sludge Test score l 1- None, base oil control Negligible 75-78 2 None, base oil plus 0.5% cornme d 71 sulphurized tcrpene corrosion inhibitor. 3- beta-Methacrylyloxyethyldiethylam- 54 monium stearate. 4.-." beta-Methacrylyloxyethyldicyclo- 50 hexylammonium stearate. 5. 90/10 Lauryl methacrylato/beta-di- Very good--. 80

ethylamincethyl mcthacrylate. 6..- 90/10 Lauryl methacrylate/beta-dido 90 1 (71) ethylaminoethyl methacrylato plus 0.5% antioxidant. 7 70/30 Lauryl methacrylate/beta-dido 78 ethylaminoethyl methacrylate. 8.- /40 Lauryl methacrylate/beta-di- Good ethylaminoethyl methacrylate. 9 50/50 Lauryl methacrylate/beta-di- Moderate... 46

ethylaminoethyl methacrylate. I 10-... 85/5/10 Lauryl methacrylate/ t-di- Good 88 methylaminocyclohexyl methacrylate/methacrylanilide. 11-... 85/15 Lauryl methacrylate/-vinyl- (lo S5 pyridine. 12 90/10 Lauryl methacrylate/-dimethyl- Very good-.. 85 2 (65) aminocyclohexyl methacrylamide. 13-". 60/40 Lauryl methacrylate/beta-dicy- --..d0 73 clohexylaminoethyl methacrylatc. 14--.- 8515/10 Lauryl methacrylate/beta-di- Good 88 1 (60) cyclohexylaminoethyl methacrylate/ methacrylanilide. 15-... 60/10/30 Lauryl methacrylate/beta-di- Moderate-.. 85

ethylaminoethyl methacrylate/styrene. 16.-.. 30/10/60 Lauryl methacrylate/beta-dido 88 ethylaminoethyl methacrylate/N- tert. octyl acrylamide.

1 Polymer additive used at 1.5% concentration in the oil.

1 Scores in are the control scores, which are obtained in each case, for the particular oil and fuel combination used when these scores differ from the main base score of -78.

Table V.-SAE-20, Duosol extracted Mid-Continent oll Lauson Polymer Engine Score 1 1. none-base oil control 58 2. none-control, base oil plus 0.5% antioxidant 63 3. 92.5/5/25 lauryl methacrylatelbeta-diethylaminoethyl mothacrylate/methacrylanilide 91 4. 89/1/101auryl methacrylate/beta-diethylaminoethyl methacrylate/methacrylauilide 81 5. /5/10 lauryl methacrylatelbeta-diethylaminoethyl methacrylate/methacrylanilide 6. 85/5/10 lauryl methacrylate/betadibutylaminoethyl mcthacrylate/methacrylanilide 85 7. 85/5/10 tridecyl methacrylate/beta-diethylaminoethyl methacrylate/methacrylanilide 90 8. 85/5/10 octadecyl methacrylate/betadiethylaminoethyl mcthacrylate/methacrylanilide 82 9. 65/10/25 lauryl methacrylate/beta-diethylaminoethyl methacrylate/N-tert.-octylacrylan1ide 90 10. 85/10/5 lauryl methaerylate/methacrylanilide/glycidyl iietliaicrylate reacted with secondary cocoamine (see 82 x. 11. 85/5/l0laurylmethacrylate/diallyl amine/methacrylanilide. 80 12. 90/10 lauryl methacrylate/N-( t-dimethylominocyclo- 1 85 hexyl) methacrylarm'de Polymer added at 1.5% concentration. 1 N0 added antioxidant.

Table IlI.SAE-20, Duosol extracted Mid-Continent oil No. Polymer Added fgg Slope figggffgg Lauson Score 1 None, base oil control 97. 15 min 52-58 av. 55. /5 n-Decylacrylato[p-dimethylaminomethylstyrene- 116.0 5. 7 Good 79 E1? 95/5 Lauryl mathacrylate/p-dimcthvlaminomethylstyrene 118.0 6.1 Very good... 82 1 85/5/101Lau1ogr1 methacrylatelp-dimethylamlnomethylstyrene/meth- 131.0 4. 48 Good 82. 1

acry am 1 e.

62.4/20.4/17.2 Lauryl ethyl maleate/beta-diethylaminoethyl meth- 110.0 3. 1 Very good...

acrylate/ethylene.

93/7 Lauryl turnarate/beta-diethylaminoethyl mcthacrylate 115.0 6. 9 do 85/15 Llattlryl methacrylate/beta (alpha-methylbenzyl) ethyl meth- 110.0 .do

QCIY 3. e.

85/10/5 Lauryl methacrylate/methyacrylanile/glycidyl methac- 145. 0 4. 04 84.

rylate reacted with diamylamine (see Ex. III).

75/25 Lauryl methacrylatelbeta-dimethylaminoethyl methacrylate 80 (1%).

85/5/l10 1I iuryl methacrylatc/2-methyl-5-vinyl pyridine/methac- 70 (1%).

ry anii c.

1 Unless otherwise noted in parentheses, Lauson scores are obtained on lubricant compositions containing 1.5%, by weight of base oil, of the added polymer.

Table VI.SAE20, Duosol extracted Mid-Continent Table VIl.-SAE-20 Duosol extracted Mid-Continent oil il.Continued I ESTER LUBRICANT (DI-2-ETHYLHEXYL SEBACATE) Preformed Polymer sludge Test Viscosity in V V Centistolres Vis- No. Polymers cosity Slope 1. None, base oil control .15 minutes. Index 2. beta-di(2-ethylhexyl)aminoethyl methacrylate Negligible. 1 100 F. 210 F. 3. beta-methacrylyloxyethyldi(Z-ethylhexyl) ammo. Do.

nium stearate.

4. 97.5/25 lauryl methacrylate/beta-diethylamincethyl Good. 1 Di-Z-ethylhexyl sebacate 12.75 3.36 156.0

methacrylste. (control).

5. 80/20 Sec. eapryl methaerylate/beta-diothylamnio- Do. 2 50/50 n-Deoyl acrylate/beta- 16.52 4. 22 183.0 4.38

ethyl methacrylate. diethylaminoethyl meth- 6. 00/10 decyl methacrylate/beta-dlethylammoethyl Very good. aerylate methacrylate. I 3 50/48/2n-Decyl acrylate/beta- 16. 60 4. 26 184.0 4.35 7. 80/20 trideeyl methacrylate/bota-diethylaminoethyl Do. diethylaminoet-hyl m w.

methacrylate. 1 5 aerylai:e/Inethaerylanilide. 8. 80/20 hexadeeylmethaerylate/beta-diethylannnoethyl Do. 4 85/5/10 Laurylmethacrylate/ 22.22 5.81 182.0 3. 87

nletnaerylate. beta-diethylamino-ethyl 0. 80/20 oetadeeyl methocrylatefbeta-diothylaminoethyl Do. matham-flate/methacrymm methacrylate. ilide. 10. 80/20 octadeoenyl mothacrylate/beta-diethylamino- Do.

ethyl methaorylate.

99/10 lmlryi y /W- m y Polymer added at 3% concentration based on the oil rather than at aminopropyl mothacrylaie. 1.5% concentration.

12. 80/20 lauryl methacrylate/tert. oetylaminoethyl meth- Do. b y l bi r acrylute- This illustrates-the use of 30% of unmodified styrene in a polymer 35/15 l y Y p y y G006 additive without undue loss in solubility anti other desirable properties.

fifi y methflcrylfltfi; 4 Alkylation of styrene, however, improves the oil-solubility of its couoly- 144 y'l fumallmlbeta illflthylamlllfilefllyl 111mm- E mors and oil-soluble products can be obtained by the eopolymerization W e f with suitable amine-containing monomers. Particularly desirable prod- 90/10 Vinyl Inmate/WHY] beta-dlmethylflnlllloethyl nets are obtained by the copolymerization of an amine-containing monoethcr. a I war with an alkyl styrene having an alkyl group of seven to twelve /29 y y ether/Vinyl beta-dletflylalllll'loethyl' (300dearbon atoms attached to the benzene nucleus as in No. 13.

05116-1 Polymenadded at 3% concentration based on the lubricant rather 17. 07/33 liln olollietxylstyreno/beta(tort. octylammo)ethyl Moderate. t t; 1,5% trati met aorya e. 1 is. 00/10 dodecylstyreno/beta-diethyl-aminoethyl mBl-ll- Do. The effectiveness of tee luoncant compositions of this aorylate. a

19. 07/3 lanryl methaerylate/vinyl beta-aminoethyl ether- Good. 30 m may further the carbon Suspen sion test used .in the lubricating oil field as a standard bench test to determine detergent activity. in this test 30 grams of a carbon black is pebble-milled for 24 hours with sufficient refined white mineral oil to make a thin paste (usually 300400 grams required). A IO-gram portion of the resulting paste is placed in a 4-ounce petroleum sample bottle, 0.2 gram of the particular poly- Talme VII.SAEZ0, Duosol exfracted filial-Continent being 'tested (dlssolved kemsene) added f Oil bottle filled to the shoulder With kerosene, the resulting 40 suspension shaken well, and the rate of settling observed.

in Tac-le VIII below results of this carbon suspension dsc si ti in test are given which show the effectiveness of polymers N0 Polymers 0 es g. slope used in the instant invention, even where one or more of 100 F 210 F lndeX the components of the polymer are present only in relatively small proportion. Thefigurcs represent the percent I of the total volume of the test suspension in which settling 1 None,baseoilcontrol 417.0 i

2 i Lauryl met-nae! 7562 1185 137.0 L2 1191 :visible after the period indicateo.

lafe/bega-fgrmamidoet 1- y viny et er.

3 95 5 Vinyl laurate/beta-(ii- 76 7.15 111.0 4.84 Table VIII ethylaminoethyl methl ll t ll 1 l 0 6 7 21 110 0 6 i my aura ea y g y- 5. u o. 5 1 3 48 72 7 l reacted i Polymel hour hours hours hours hours days (liamylazmne (See Ex. v

5 90/10 Lauryl methacrylate/ 55. 59 8.59 129.0 1.28

s y dyl a y 1. 90/10 dodeeylstyreue/betadiagte i y eihylamnoethyl priethacryl- $68 #1 210 see xamole a 100 100 9G 6 /5/10 Lauryl inethacry- 50.06 7.41 114.0 4.44 55 2 7 2 lauryl g mm le el l y e/ ,beta-diethylaminoethylmethtlfirylimllldeaerylate/methaorylanilide 100 100 79 67 37 7 64/l8/l 8 LuL'i'Yl methacryl- 59.89 3.5:) 121.0 G. 5 3 lag/ 51 5 muryl methacrylate/ e/ oeta-dlmethylammo beta-diethylaminoethyl meniet y et wv el aciylate/methacrylanilide 100 so s0 67 33 one (See Ex. VI). I 4. Lauryl methacrylate (con- 8 69/104/140 2Ethylliexylac- 01-5-3 1. :1 111-0 0-1 60 m1 100 93 n 13 12 10 ryl e/be y ln 5. None-blank 27 19 14 ethyl methacrylate/rsobutylene (See EX. .VI). r

108") It will be observed that polymers containing as little ether. as 0.5% of the basic amino nitrogen-containing com- 'g gl ggg 13M 5 ponent, show appreciably improved detergent activity 11'] I v 1 1' nyletherlbletafi'ormaroiciocomparison wlth both the blank and me unmodified ethy viny et er. t l

(JO/10 gecscaprylb methw 660 M07 1320 5. 42 lauryl melhacrylate control, being about bet er than rylate/beta-diethylaminothe-biankafter 24 hours and, even after days, 52111 more gfll f gf (See than 300% better than unmodified lauryl methacrylate 12- 5042060 Tridecyk ll inethacrgg 53.38 7.81 119.0 5.1 polymer.

at beta-diet y aminoe Y1methacryme/styreneu It will be understood that wh le the foregoing examples g sbee llgx VIIfl. Vb t O2 8 78 0 4 :1 and tables have disclosed a considerable number of specific g fgfiiljgfgg fi j ij a polymers adapted for use in the composition of the presacrylate (See Ex. IX). cnt invention, these are merely illustrative and that the Wen 75 .present invention broadly comprises a lubricating oil containing at least 0.1% by weight thereof of an oil-soluble, basic amino nitrogen-containing addition-type polymer of a plurality of polymerizable ethylenically unsaturated compounds at least one of which is amine-free and contains from 8 to about 18 carbon atoms in an aliphatic hydrocarbon chain, which in the polymer is not part of the main polymer chain, the polymer containing 0.1% to 3.5%, by weight thereof, of basic amino nitrogen.

The polymers used in the present invention are actually copolymers derived from at least two different polymerizable compounds one of which must be amine-free, at least one of which must contain at least 8 carbon atoms in an aliphatic chain which in the polymer does not form part of the main chain, thereby providing an oleophilic structure, and at least one of which must contain a basic amino nitrogen structure, and the copolymers must contain at least 0.1% but not more than 3.5%, by weight thereof, of basic amino nitrogen, preferably between 0.2% and 3.0%. The polymer can be derived from not only two difierent polymerizable compounds as above but also from one or more additional polymerizable compounds that do not by themselves form oil-soluble polymers, providing the proportions are restricted to insure that the polymers have the requisite oil solubility and that no substantial change in the valuable properties of these polymers as sludge dispersants and viscosity index improvers. A basic requirement is that the copolymer formed must have at least a limited solubility in the oil, i. e., at least 0.1% by weight. The term oil-soluble is used herein to denote a solubility of at least 0.1%, by weight, of the polymer in the oil.

As the oleophilic components of copolymers useful in the preparation of the improved lubricating compositions of this invention there can be employed polymerizable esters, amides, ethers, and hydrocarbons characterized by the presence of at least eight carbon atoms, preferably with six or more in a straight chain, and at least one carbon-carbon double bond capable of participation in free radical initiated addition copolymerization reactions. Examples of oleophilic components that come within the purview of this invention are: saturated and unsaturated long-chain esters of unsaturated carboxylic acids such as decyl acrylate, 3,5,5-trimethylhexyl methacrylate, 9-octadecenyl methacrylate; unsaturated esters of long-chain carboxylic acids such as vinyl stearate; long-chain esters of vinylene dicarboxylic acids such as methyl lauryl furnarate; N-long-chain hydrocarbon substituted amides of unsaturated acids such as N-octadecyl acrylamide; long-chain monoolefins such as the alkyl or acyl substituted styrenes, e. g., dodecylstyrene, and the like. Obviously, these components can be employed alone or in various combinations and, in general, make up the majority of the polymeric additive in order to insure proper oleophilic character. The technical lauryl methacrylate obtained from the commercial mixture of long-chain alcohols in the C10 to C18 range derived from coconut oil is an especially useful oleophilic component of the copolymer but the group of acrylic and alkacrylic esters of aliphatic alcohols of at least eight carbons are, in general, Well suited as the oleophilic component of the copolymer.

The basic amino nitrogen-containing component that imparts sludge dispersant properties to the polymers useful in this invention, can be introduced through the use of appropriate copolymerizable monomers containing primary secondary or tertiary amino nitrogen that is attached ultimately to the chain of the polymer as part of an extralinear substituent group in which the nitrogen is joined extranuclearly only to non-benzenoid carbon atoms. There can be employed in the copolymerization monomers such as glycidyl acrylate or vinyl chloroacetate which introduce groups reactive toward ammonia or amines and thus provide a means of attaching the necessary basic amino groups to the polymer chain. Attachment of the amino groups to the main copolymer carbon chain can be through strictly hydrocarbon structures or through ether, ester, or amide linkages.

Particular examples of the basic amino-containing monomers include the basic amino substituted olefins such as p-(beta-diethylaminoethyl)styrene; basic nitrogencontaining heterocycles carrying a polymerizable ethylenically unsaturated substituent, e. g., the vinyl pyridines and the vinyl alkyl pyridines such as 2-vinyl-5-ethyl pyridine; esters of basic amino alcohols with unsaturated carboxylic acids such as the alkyl and cycloalkyl substituted aminoalkyl and cycloalkyl esters of the acrylic and alkacrylic acids, e. g., beta-methylaminoethyl acrylate, 4-diethylaminocyclohexyl methacrylate, beta, beta-didodecylaminoethyl acrylate, and the like; unsaturated ethers of basic amino alcohols such as the vinyl ethers of such alcohols, e. g., beta-aminoethyl vinyl ether, beta-diethylaminoethyl vinyl ether, and the like; amides of unsaturated carboxylic acids wherein a basic amino substituent is carried on the amide nitrogen such as N-(beta-dimethylaminoethyl)acrylamide; polymerizable unsaturated basic amines, e. g., diallylamine, and the like.

In this specification and claims the term basic amino nitrogen is used in the generic sense to cover the primary, secondary and tertiary amines including, as stated above, the basic nitrogen-containing heterocycles.

Because of their relatively greater basicity and more effective sludge suspending properties, the polymerizable ethylenically unsaturated compounds containing a basic tertiary amino group are preferred and those having only primary basic amino groups are least desirable. Particularly outstanding and readily available basic amino nitrogen-containing components are the alkyl and cycloalkyl substituted tertiary aminoalkyl and cycloalkyl esters of acrylic and alkacrylic acids.

The basic amino nitrogen-containing component of the copolymer must be present in a minor proportion by weight corresponding to no more than 3.5% and no less than 0.1% of basic amino nitrogen by weight of the polymer. Above the higher level, which, for example, corresponds to about 50% by weight of amino monomer in a lauryl methacrylate/beta-diethylaminoethyl methacrylate copolymer, and at less than the lower level, the performance of the polymer as an oil detergent falls off rapidly. It is preferred that the basic amino nitrogen content be within the range of 0.2% to 3.0% by weight of the polymer.

The oil detergent polymers used in this invention can contain limited amounts of copolymerizable components that do not necessarily contribute either to improve solubility or detergent action but merely serve as fillers or extenders for the active components. Typical examples of these filler components include the well-known shorter-chain ethylenically unsaturated addition polymerizable monomers such as the vinyl and allyl formates, acetates, propionates, butyrates, and the like; polymerizable unsaturated short-chain hydrocarbons, e. g., the monoolefins such as ethylene, propylene, isobutylene, styrene, vinyltoluene, and the like, and the short-chain dienes such as 1,3-butadiene, isoprene, and the like; unsaturated short-chain carboxylic acids and their derivatives such as the alpha-rnethylenecarboxylic acids and their derivatives, e. g., acrylic acid, methyl methacrylate, acrylonitrile, methacrylamide, and the like; the shortchain unsaturated ethers, particularly the vinyl and allyl ethers, e. g., ethyl vinyl ether, butyl vinyl ether, and the like. These and other familiar monomers that are avail able at moderate cost can be employed for this purpose in proportions ranging up to as much as 79%, by weight, in representative polymers although it is preferred they should not exceed 65% by weight of the polymer.

In addition, inclusion of minor proportions of N-hydrocarbon-substituted amides of unsaturated carboxylic acids will be found beneficial, particularly if exceptional improvement of the lubricating oil with respect to viscosproving the elficiency of lubricating oils.

ity index is desired. Especially suitable as polymerizable components of the polymer are the N-hydrocarbon-substituted acrylamides including N-tertiary-butylacrylamide, N-tertiary-octylacrylamide, and, particularly, the N-aryl-acrylamides such as methacrylanilide and acrylanilidc.

The polymers employed in the improved lubricating compositions of this invention can be represented by the following schematic formula:

wherein M is the structural unit joining the various substituent groups to the main chain of the polymer, R is the required oleophilic structure, Rb is the basic amino containing structure that imparts sludge dispersency, and Re is the optional extenderstructure; and x, y and z represent the proportions of these various structures in the polymer. M can be anether, ester or amide group and n is a cardinal number no greater than 1, i. e., 0 or 1; R0 is a straight or branched chain hydrocarbon radical of from 8 to about .18 carbon atoms, Re is a monovalent organic radical free of reactive hydrogen and is preferably a solely hydrocarbon radical of less than 8 carbon atoms and when n is 0, Re can be hydrogen; and Rb is a primary, secondary, or tertiary amino radical of the structure in which the nitrogen is bonded extra-nuclearly only to hydrogen or aliphatic carbon and in which A is a hydrocarbon radical of 1-18, preferably 2 to 6 carbon atoms, B and D are hydrogen or hydrocarbon radicals of no more than about 18 and, preferably, no more than 6, carbon atoms, and B or D can be joined with A to form a heterocycle. The proportions of the various structures inthe polymer, as represented by x, y and z in the schematic formula, normally will be in the range: x from 20% to 99%; y from 0.5% but, preferably, from 1% to 50%; and z from 0% up to 79% but, preferably, only up to 65%, all percentages being by total weight of the polymer. Within these ranges, optimum proportions will be determined both by the properties contributed to the polymer by the individual polymerizable components going into its composition and the particular properties of the polymer which it is desired to emphasize.

An advantage of the present invention is that it providesan economical and practical means of greatly im- An outstanding advantage of the invention is its improvement of lubricating oils for use in internal combustion engines,

particularly under low-duty driving conditions. Under these severe operating conditions, which account for the majority of present day driving, an extremely high rate of sludge formation and subsequent deposition on moving .engine parts is encountered. The deposits thus formed are quite deleterious to engine operation resulting in overall sluggish behavior and particularly in oil ring clogging leading to excessive oil consumption and in oil screen plugging resulting in circulatory failure with subsequent bearing destruction. The lubricating compositions thus far available have proven singularly inefifective in combating these low-duty operating problems. Th

lubricating oil compositions of this invention by preventing the undesirable sludge and varnish deposition .Gfier the only known solution to this diflicult problem.

The instant lubricating oil compositions have a further advantage in that the polymer additive does not de posit inorganic ash; whereas, many of the known oil detergents, which are of questionable utility under lowduty operating conditions, deposit inorganic ash and actually-contribute to the accumulation of undesirable noncombustible material in the engine. Finally, the lubricating oil compositions of the present invention also exhibit markedly improved viscosity characteristics, a desirable feature often achieved by the use of special additives. in particular, the dispersive polymer additives improve the viscosity index of the lubricating oils while still maintaining a relatively low viscosity at atmospheric temperature. However, these latter advantages are subordinate to the detergent properties of these compositions and especially to their low-duty performance.

As many apparently widely dilferent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments except as defined in the appended claims.

The invention claimed is:

l. A petroleum base lubricating oil containing at least 0.1% by weight of an oil soluble, basic amino nitrogencontaining addition type copolymer containing in combined form as its essential monomeric components copolyincrizabie ethyienically unsaturated compounds each containing only one polymerizable ethylenic linkage, at least one of which components is amine-free and contains from 8 to about 18 carbon atoms in an aliphatic hydro-carbon chain which in the copolymer is not part of the main chain, and one of the components as it exists in the copolymer containing a basic aminonitrogen in the side chain, said copolyrner containing 0.1% to 3.0% by weight of basic amino nitrogen, said copolymer having an inherent viscosity of 10.1 to 3.0 as determined at 0.1% weight/volume concentration in benzene at 25 C., and said copolymer being one which does not contain as a component a N-hydrocurban-substituted acrylamide.

2. A petroleum base lubricating oil as set forth in claim 1, wherein 0.25% to 10% of said copolymer is incorporated in said lubricating oil and said copolymer has an inherent viscosity of 0.2 to 1.0 as determined at 0.1% weight/volume concentration in benzene at 25 C.

3. A petroleum base lubricating oil in claim 1 in which the basic amino nitrogen in the side chain of the copolymer is in teritary amino group.

4. A petroluem base lubricating oil containing at least 0.1% by weight of an oil soluble, basic amino nitrogencontaining addition type copolymer containing in combined form as its essential monomeric components ccpolymerizable ethylenically unsaturated compounds, one of which is from the group consisting of acrylic and alltacrylic esters of aliphatic alcohols of from 3 to about 13 carbon atoms and one of the components containing a basic teritary amino group in the side chain, said copolymer containing 0.1% to 3.0% by weight of basic amino nitrogen, said copolymer having an inherent viscosity of fzlto 3.0 as determined at 0.1% weight/volume concentration in benzene at 25 C., and said copolymer being one which does not contain as a component a l t-hydrocarbon-substituted acrylarnide.

5. A petroleum base lubricating oil containing at least 0.l% by weight of an oil soluble, basic amino nitrogencontaining addition type copolymer containing in combined form as its essential monomeric components copolyiuerizable ethyieuically unsaturated compounds, one of which is from the group consisting of acrylic and alkacrylic esters of aliphatic alcohols of from 8 to about :8 carbon atoms and one of the components is from the group consisting of alkly and cycloalkyl substituted tertiary aminoallzyl and amino CYClDttllQ/i esters of acrylic and alitacrylic acids, said copolymer containing 0.1% to 3.0% by weight of basic amino nitrogen, said copolymer having an inherent viscosity of 0.1 to 3.0 as determined at 0.1% Weight/volume concentration in benzene at 25 C., and said copclynier being one which does not contain as a component a Nhydrocarbon-substitutcd acrylamide.

6. A petroleum base lubricating oil containing from 025% to 10% by weight of an oil soluble, basic amino nitrogen-containing, additional type copolymer containing in combined form as its essential monomeric components copolymerizable ethylenically unsaturated compounds, one of which is from the group consisting of acrylic and alkacrylic esters of aliphatic alcohols of from 8 to about 18 carbon atoms and one of the components is beta-diethylaminoethyl methacrylate, said copolymer containing 0.1% to 3.0% by weight of basic amino nitrogen, said copolymer having an inherent viscosity of 0.1 to 3.0 as determined at 0.1% Weight/ volume concentration in benzene at 25 C., and said copolymer being one which does not contain as a component a N-hydrocarbonsubstiuted acrylamidc.

7. A petroleum base lubricating oil containing from 0.25% to 10% by weight of an oil soluble, basic amino nitrogen-containing addition type copolymer containing in combined form as its essential monomeric components copolymerizable ethylenically unsaturated compounds, one of which is lauryl methacrylate and one of which is beta-diethylaminoethyl methacrylate, said copolymer containing 0.1% to 3.0% by weight of basic amino nitrogen, said copolymer having an inherent viscosity of 0.1

18 to 3.0 as determined at 0.1% weight/volume concentration in benzene at C., and said copolymer being one which does not contain as a component a N-hydrocarbon-substituted acrylamide.

8. A petroleum base lubricating oil as set forth in claim 1, containing from 0.1% to about by weight of the oil soluble basic amino nitrogen-containing addition type copolymer.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,627 Bruson Aug. 31, 1937 2,104,796 Dietrich Jan. 11, 1938 2,291,214 Dietrich July 28, 1942 2,311,548 Jacobson Feb. 16, 1943 2,489,281 Foehr Nov. 28, 1949 2,584,968 Catlin Feb. 12, 1952 2,613,184 Catlin Oct. 7, 1952 2,653,133 Catlin Sept. 22, 1953 2,666,044 Catlin Jan. 12, 1954 

1. A PETROLEUM BASE LUBRICATING OIL CONTAINING AT LEAST 0.1% BY WEIGHT OF AN OIL SOLUBLE, BASIC AMINO NITROGENCONTAINING ADDITION TYPE COPOLYMER CONTAINING IN COMBINED FORM AS ITS ESSENTIAL MONOMERIC COMPONENTS COPOLYMERIZABLE ETHYLENICALLY UNSATURATED COMPOUNDS EACH CONTAINING ONLY ONE POLYMERIZALE ETHYLENIC LINKAGE, AT LEAST ONE OF WHICH COMPONENTS IS AMINE-FREE AND CONTAINS FROM 8 TO ABOUT 18 CARBON ATOMS IN AN ALIPHATIC HYDRO-CARBON CHAIN WHICH IN THE COPOLYMER IS NOT PART OF THE MAIN CHAIN, AND ONE OF THE COMPONENTS AS IT EXISTS IN THE COPOLYMER CONTAINING A BASIC AMINO NITROGEN IN THE SIDE CHAIN, SAID COPOLYMER CONTAINING 0.1% TO 3.0% BY WEIGHT OF BASIC AMINO NITROGEN, SAID COPOLYMER HAVING AN INHERENT VISCOSITY OF 0.1 TO 3.0 AS DETERMINED AT 0.1% WEIGHT/VOLUME CONCENTRATION IN BENZENE AT 25*C., AND SAID COPOLYMER BEING ONE WHICH DOES NOT CONTAIN AS A COMPONENT A N-HYDROCARBON-SUBSTITUTED ACRYLAMIDE. 